Protective composition for metals



United States Patent l 3,535,925 Patented R'Iay 22, 1952 3,035,926 PROTECTIVE COMPQSITION FOR METALS Leslie J. Larrieu, San Marino, Calif., assignor to Morris P. Kirk & Son, Inc., Los Angeles, Calif., a corporation of California No Drawing. Filed Jan. 4, 1960, Ser. No. 68 Claims. (Cl. 106-14) This invention relates to a composition of the type applied to surfaces of metals to protect the same against corrosion, and especially a temporary protective composition that can be used to protect metals during periods of storage or transportation and can at any time be quickly and conveniently removed from the metals being protected.

Machined or formed metal parts of all kinds require protection against corrosion when placed in storage or when set aside for indefinite periods of time. This is es pecially true of tools and dies used in the production of high precision metal or plastic parts. For example, forming dies used in the fabrication of metal parts for aircraft construction have suffered an acute need of a satisfactory method of protection from corrosive attack by the elements.- It is essential that the protective composition remain in place upon the metal surfaces after application thereto to adequately prevent corrosion thereof. It also is imperative that the protective composition be unreactive toward the metal, resistant to oxidation, easy to apply, and readily removable without injury to the metal surfaces to which it has been applied. Although all metals suifer from corrosion when stored in the atmosphere, zinc, which comprises the base element of forming dies used in the fabrication of metal parts for aircraft construction, is subject to severe attack by outdoor atmospheric conditions, and especially humid climatic conditions. Furthermore, zinc becomes anodic in most electrolytic systems and is, consequently, the sacrifi cial member of such electrolytic systems.

The method generally practiced for storing zinc base forming dies includes pressing a male lead punch upon a mating female die and placing the resulting set outdoors for storage under atmospheric conditions. The resulting set in the presence of moisture and other atmospheric elements offers the basic essentials for producing a crude electrolytic cell when water collects in the usually basinlike configuration of the die. As a result, costly destruction of such zinc base dies is continuously in process. Corrosion preventive agents presently being employed in an attempt to prevent such costly destruction have proven themselves to be unsatisfactory. Most of the prior art preparations do not remain in place upon the metal surfaces to which they have been applied. Moisture, water vapor, dust and other atmospheric pollutants either remove or penetrate the protective films of prior art composition during storage of the metal parts and destructive corrosion takes place without warning in an objectionably short time. More adherent prior art compositions, such as paints (bitumastic paints, for example), lacquers, varnishes and enamels, often are ineffective in preventing corrosion and are difiicult or troublesome to remove from the coated metal.

Accordingly, it is an important object of my invention to provide a composition for the prevention of corrosion of metals which can be rapidly and conveniently applied to the surfaces of metal parts and will remain in position upon such surfaces for prolonged periods of time.

Another object of my invention is to provide a metal coating which will eifectively prevent corrosion of the metal and which can be rapidly and conveniently removed from the protected metal.

A further object of my invention is to provide a composition for the prevention of corrosion of metals which includes a corrosion inhibitor and an absorbent material, which retains quantities of the inhibitor in reserve supply for continuous, slow release of adequate amounts of the inhibitor to the metal to insure protection of the metal against corrosion for prolonged periods of time.

Additional objects will become apparent from the following description, which is given primarily for purposes of illustration and not limitation of my invention.

Briefly stated in general terms, the objects of my invention are attained by providing a composition for preventing corrosion of metals comprising a major amount of an oleaginous material intimately mixed with a minor amount of solid particulate material and a small amount of corrosion inhibitor.

The oleaginous material generally is present in the composition in the range of from about 60 to about 90 percent by weight based upon the mixture, and preferably is present in the range of from about 65 to about 85%, and especially about Such materials include animal, vegetable and mineral oils, fats and Waxes. Lanolin, beeswax and lard oil are examples of suitable animal sources of oleaginous materials; linseed oil, tung oil, dehydrated castor oil and soyabean oil are suitable examples of vegetable origin materials, and petrolatum and petroleum oils are examples of suitable mineral derived materials. Hydrogenated vegetable oils also are satisfactory oleaginous materials. However, it is preferable, espe cially in connection with the production of the zinc base alloy parts, such as the forming dies and tools used in connection with the production of metal parts for the aircraft industry to use Water soluble oils, such as sulfonated oils of the types mentioned immediately above and especially sulfonated mineral oils, for example.

' When using water soluble oils, I prefer to employ from about 65 to about by weight of the mixture in the corrosion preventive composition of my invention, and especially about 75%. The oleaginous material serves to form a paste of the desired consistency for application to the surface of the metal to be protected by dipping, spraying or brushing the paste onto the metal surface. The oleaginous material also serves to form a sticky protective film over the surface of the metal part to exclude moisture, atmospheric oxygen, dirt and other atmospheric pollutants of objectionable chemical characteristics from coming in contact with the metal surface. The water soluble oils in addition appear to insure uniform and continuous spreading and contacting of the metal surface with the inhibitor present in the composition, as will be described below. The inhibitor, of course, acts together with the oil film to prevent corrosion of the metal at its surface.

The solid particulate material in the composition of my invention serves to absorb or adsorb the inhibitor so that it is retained in reserve for slow distribution and insured protection of the metal surfaces to be protected over a prolonged period of time under adverse atmospheric conditions. Among suitable particulate materials are fullers earth, kieselguhr, diatomite, Attapulgus clay, talc, adsorptive carbon, silica gel, and so forth. The particulate matter should be unreactive with the metals to be protected from corrosion and should be finely divided so that the particle size thereof is sufficiently small to penetrate cracks and crevices of the metal parts to be protected. The particulate matter may make up from about 10 to about 40% by weight of my protective composition and preferably is present in the amount of from about 15 to about 35% by weight and especially about 25%. I have found that diatomaceous earth is an especially good particulate material to use with water soluble oil in con- 3 nection with the protection of metal parts made with zinc base alloys.

Various corrosion inhibitors have been used to protect metals from corrosion of the type discussed hereinabove. A commonly known inhibitor is one containing chromate ion. As used herein, the term chromate is intended to include dichromates because of the close relationship between chromates and dlchromates and their very similar action as corrosion inhibitors. Another inhibitor that can be used is one containing the nitrite ion and a further inhibitor which has been proven satisfactory for such purposes is one containing the benzoate ion. It will be understood that other inhibitors can be used, such as those commonly known as anodic and cathodic inhibitors, which inc.ude such materials as alkalis, such as lime, and sodium hydroxide or carbonate for protecting steel. Other inhibitors include sodium sulfite, hydrazine hydrate, sodium polyphosphates, sodium silicate, etc. The inhibitor generally is present in very small amounts in the range of from about 0.5%, or less, to about 2.5%, or more, by weight of the mixture making up the composition. I have found that chromates such as sodium chromate, potassium chromate, sodium dichromate and potassium dichromate are particularly suitable for use in the compositions of my invention in the range of from about 1% to about 2% by weight based on the mixture, preferably about 1.2 to about 1.5%. Similar amounts of sodium nitrite or potassium nitrite and somewhat larger amounts of sodium benzoate can be used. Also, mixtures of sodium nitrite and sodium benzoate are satisfactory when used in somewhat larger amounts, such as about 5% by weight of the mixture. Chromate and dichromate inhibitors when used with the amounts of water soluble oils and diatomaceous earth described hereinabove have been found to be especially satisfactory for making up compositions to protect zinc base alloy parts, especially when stored in connection with lead punch and zinc base die sets as described hereinabove.

In another preferred embodiment of my invention, preferably employing a water soluble oil as the oleaginous material, a significant amount of water is included in the corrosion preventive composition together with a significant amount of a solid particulate material and a minor amount of a corrosion inhibitor. The amount of water generally present in compositions of this embodi ment ranges from about 5 to about 50 percent by weight based upon the mixture and preferably is present in the range from about to about 40%, and especially from about 25 to about 35%. The amount of oleaginous material ranges from about 35 to about 85% by Weight based upon the mixture, preferably from about 45 to about 75%, and especially from about 50 to about 60%. Similarly, the amount of solid particulate material varies from about 5 to about 40% by Weight based upon the mixture, preferably from about 10 to about 30% and in particular from about 10 to about The inhibitor is present in small amounts in the range of from about 0.5%, or less, to about 2.5%, or more, by weight of the mixture, preferably from about 1 to about 2%, and particularly from about 1.2 to about 1.5%.

Various methods of making the protective compositions of my invention can be used. They Will vary in accordance with the various components employed to make the composition. For example, the absorptive material, such as diatomaceous earth, is ground or otherwise comminuted to produce a particulate material having the desired particle size. The resulting particulate material is mixed with a measured amount of inhibitor, such as sodium dichromate and ground either dry or in the presence of a small amount of moisture. The particulate absorptive material in this process becomes well filled or saturated as well as coated with the inhibitor. The resulting mixture of inhibitor and particulate material is well mixed with a sulfonated oil, other water soluble oil, or

other oleaginous material by the use of a suitable mechanical mixing device.

A particularly preferred method of producing the composition of my invent-ion is as follows. A measured amount of sodium dichromate is dissolved in a measured amount of water. The resulting solution is added to a measured amount of diatomaceous earth and mixed mechanically to produce a stiff slurry. The resulting slurry then is added to a measured amount of sulfonated oil and the resulting material is thoroughly mixed with mechanical agitation to produce a uniform stable suspension of paintlike consistency. The following examples, which afiord corrosion protection to metals, additionally illustrate specific embodiments of my invention. The composition figures are percent by weight based upon the mixture in the composition.

EXAMPLE I Percent Water soluble oil 74.0 Sodium dichromate 1.3

Diatomaceous earth 24.7

The properties of the water soluble oil employed in the composition of Example 1 immediately 'above are shown in Table 1 below:

Table 1 A.P.I. gravity 21.4 Flash poin F 225 Saybolt viscosity 100 F 299 Saybolt viscosity 200 F 49.4 Pour p n F..- --20 Color (A.S.T.M.) A+ Viscosity index 66 EXAMPLE II Percent Petrolatum 70.2 Sodium nitri 1.5 Fullers earth 28.3 EXAMPLE III Lanolin 68.1 Sodium chromate 1.8 Activated clay 30.1 EXAMPLE 1V Medium grade motor oil 75.3 Sodium benzoate 2.2 Activated carbon 22.5

EXAMPLE V Castor oil 73.5 Sodium dichrom 1.4 Silica gel 25.1

EXAMPLE VI Percent Sodium dichrom 1.4 Diatomaceous ear 14.1 Water 28.2 Sulfonated oiL 56.3

The sulfonated oil employed in the composition of Example VI immediately above complied with Federal Specifications VV-C846 and had the properties shown 70 in Table 2 below:

Table 2 Appearance Clear. Gravity, API 23.0. Color, ASTM 4.5.

Table 2Continued Viscosity, Saybolt, 100 F 210.

Sulfated residue, percent by Weight.. 1.1.

Corrosion, copper, F.S. 530.6 Extremely slight discoloration.

Corrosion, steel, F.S. 530.6 Pass.

Stability, 16 hrs., at 20 to 25 F Do.

The following aditional examples illustrate additional compositions containing water which provide corrosion protection to metals.

In an additional embodiment of my invention, the oleaginous component of both the water-free and the water-containing compositions described above are made up of at least one non-drying oil portion and at least one drying oil portion. I have found that the use of a drying oil portion in the oleaginous component of the composition of either embodiment described above causes the formation of a. protective crust over the corrosion preventive coating after it has been applied to the metal surface to be protected. Atmospheric oxygen acts upon the drying oil, such as linseed oil, tung oil, soyabean oil, castor oil, etc., employed and forms a thin, but strong, surface crust. This surface crust increases the durability and reliability of the protective coating, especially with regard to withstanding the washing client of rain upon the coating, particularly when applied to vertical or steeply sloping metal surfaces.

In general, the total amount of oleaginous material employed in the compositions of this third embodiment a is the same as that employed in the compositions of the first two embodiments described above. The ditlerence resides in the use of from about 5 to about 50% by Weight of the total oleaginous mixture of a drying oil, the remainder being a non-drying oil, such as a mineral oil, a water soluble oil, etc. The amount of drying oil used will depend upon various factors, such as the drying oil used, the non-drying oil used, and whether or not a small amount of a drier, such as metal soaps of organic acids, for example, lead, cobalt or manganese naphthenates, is incorporated in the oleaginous mixture. Without the use of a drier, the amount of drying oil used preferably ranges from about 15 to about 35% by weight of the oleaginous mixture, and especially from about 20 to about 30%.

The following examples illustrate water-free compositions of the third embodiment of my invention wherein the oleaginous component is part drying oil and part nondrying oil.

EXAMPLE XI Percent Water soluble oil 37.0 Linseed oil 37.0 Sodium dichromate 1.3 Diatomaceous earth 24.7

EXAMPLE XII Petrolatum 52.7 Linseed oil 17.5 Sodium nitrite 1.5 Diatomaceous earth 28.3

EXAMPLE XIII Medium grade motor oil 62.2 Tung oil 5.5 Sodium dichromate 1.2 Activated clay 31.0 Lead naphthenate 0.1

The following examples illustrate water-containing compositions of the third embodiment of my invention wherein the oleaginous component is part drying oil and part non-drying oil.

EXAMPLE XIV Percent Sodium dichromate 1.5 Diatomaceous earth 14.5 Water 25.0 Linseed oil 19.0 Sulfonated oil 40.0

EXAMPLE XV Sodium nitrite 1.6 Fullers earth 20.1 Water 31.0 Tung oil 4.7 Petroleum jelly 42.6 EXAMPLE XVI Sodium chromate 1.1 Attapulgus clay 16.0 Water 36.3 Soyabean oil 4.0 Medium grade motor oil 42.4 Cobalt naphthenate 0.2

Obviously many other modifications and variations of the present invention are possible in the light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention can be practiced otherwise than as specifically described.

What is claimed is:

l. A composition for the coating of metal articles to inhibit corrosion thereof in the presence of moisture, said composition consisting essentially of 35 to by Weight of oleaginous material selected from the group consisting of sulphonated oil, petrolatum, lard oil, linseed oil, tung oil, soya bean oil and mixtures thereof, 5% to 40% of a solid absorptive particulate material selected from the group consisting of diatomaceous earth, fullers earth, activated carbon and activated clay; .5 to 2.5% of a corrosion inhibitor selected from the group consisting of a soluble alkali metal chromate and dichromate and sulficient water to dissolve the inhibitor and impregnate the particulate material therewith.

2. A composition for the coating of metal articles to inhibit corrosion thereof in the presence of moisture, said composition consisting essentially of 45 to 75% by weight of oleaginous material selected from the group consisting of sulphonated oil, petrolatum, lard oil, linseed oil, tung oil, soya bean oil and mixtures thereof, 10% to 30% of a solid absorptive particulate material selected from the group consisting of diatomaceous earth, fullers earth, activated carbon and activated clay; 1% to 2% of a corrosion inhibitor selected from the group consisting of a soluble alkali metal chromate and dichromate and suflicient water to dissolve the inhibitor and impregnate the particulate material therewith.

'3. A composition for the coating of metal articles to inhibit corrosion thereof in the presence of moisture, said composition consisting essentially of about 56% by weight of oleaginous material selected from the group consisting of sulphonated oil, petrol atum, lard Oil, linseed oil, tung oil,-soya bean oil and mixtures thereof, about 14% of a solid absorptive particulate material selected from the group consisting of diatomaceous earth, fullers earth, activ-ated carbon and activated clay; about 1.4% of a corrosion inhibitor selected from the group consisting of a soluble alkali metal chromate and dichromate and about 28.6% of water to dissolve the inhibitor and impregnate the particulate material therewith.

4. A composition for the coating of metal articles to inhibit corrosion thereof in the presence of moisture, said composition consisting essentially of about 56.3% by weight of sulphonated oil, about 14.1% diatomaceous earth, about 1.4% sodium dichromate and about 28.2% water, to dissolve the inhibitor and impregnate the particulate material therewith.

5. The method of making a composition for use in the coating of metal articles to inhibit corrosion thereof in the presence of moisture, comprising dissolving .5 to 2.5% of a corrosion'inhibitor selected from the group consisting of a soluble alkali metal chromate and dichromate in suflicient water to dissolve the same, mixing the dissolved chromate with to 40% of a solid absorptive particulate material selected from the group consisting of diatomaceous earth, fullers earth, activated carbon and activated clay and causing the dissolved chromate to impregnate the particulate material, the impregna'ted particulate material with 35% to 85% of an oleaginous material selected from the group consisting of sulph'o'na'ted oil, petrolaturri, lard oil, linseed oil, tung oil, soya bean oil and mixtures thereof, said composition consisting essentially of the aforesaid ingredients.

6. The method of making a composition for use in the coating of metal articles to inhibit corrosion thereof in the presence of moisture, comprising dissolving 1% to 2% of a corrosion inhibitor selected from the group consisting of a soluble alkali metal chromate and dichromate in sufficient water to dissolve the same, mixing the dissolved chromate with to 30% of a solid absorptive particulate material selected from the group consisting of diatomaceous earth, fullers earth, activated carbon and activated clay and causing the dissolved chromate to impregnate the particulate material, mixing the impregnated particulate material with 45% to 75% of an oleaginous material selected from the group consisting of sulphonated oil, petrolatum, lard oil, linseed oil, tung oil, soya bean oil and mixtures thereof, said composition consisting essentially of the aforesaid ingredients.

7. The method of making a composition for use in the coating of metal articles to inhibit corrosion thereof in the presence of moisture, comprising dissolving about 1.4% of a corrosion inhibitor selected from the group consisting of a soluble alkali metal chromate and dichromate in about 28.6% of water to dissolve the same, mixing the dissolved chromate with about 14% of a solid absorptive particulate material selected from the group consisting of diatomaceous earth, fullers earth, activated carbon and activated clay and causing the dissolved chromate to impregnate the particulate material, mixing the impregnated particulate material with about 56% of an oleaginous material selected from the group consisting of sulphonated oil, petrolaturn, lard oil, linseed oil, tung oil, soya bean oil and mixtures thereof, said composition consisting essentially of the aforesaid ingredients.

8. A method of preventing corrosion of the surfaces of metallic articles comprising forming a composition consisting essentially of 35% to 85 by weight of oleaginous material selected from the group consisting of sulphonated oil, petrolatum, lard oil, linseed oil, tung oil, soya bean oil and mixtures thereof, 5% to 40% of a solid absorptive particulate material selected from the group consisting of diatomaceous earth, fullers earth, activated carbon and activated cla; .5% to 2.5% of a corrosion inhibitor selected from the group consisting of a soluble alkali metal chromate and dichromate and sufficient Water to dissolve the inhibitor and impregnate the particulate material therewith, and applying a coating of the resulting composition to the surfaces to be protected from corrosion so that the absorptive material retains the inhibitor in proximity to the surfaces to be protected and slowly releases the inhibitor to such surfaces in the presence of moisture and insures prolonged protection against corro sion of such surfaces.

9. A method of preventing corrosion of the surfaces of metallic articles comprising forming a composition consisting essentially of 45% to by weight of oleaginous material selected from the group consisting of sulphonated oil, petrolatum, lard oil, linseed oil, tung oil, soya bean oil and mixtures thereof, 10% to 30% of a solid absorptive particulate material selected from the group consisting of diatomaceous earth, fullers earth, activated carbon and activated clay; 1% to 2% of a corrosion inhibitor selected from the group consisting of a soluble alkali metal chromate and dichromate and sufficient water to dissolve the inhibitor and impregnate the particulate material therewith, and applying a coating of the resulting composition to the surfaces to be protected from corrosion so that the absorptive material retains the inhibitor in proximity to the surfaces to be protected and slowly releases the inhibitor to such surfaces in the presence of moisture and insures prolonged protection against corrosion of such surfaces.

10. A method of preventing corrosion of the surfaces of metallic articles comprising forming a composition consisting essentially of about 56% by weight of oleaginous material selected from the group consisting of sulphonated oil, petrolatum, lard oil, linseed oil, tung oil, soya bean oil and mixtures thereof, about 14% of a solid absorptive particulate material selected from the group consisting of diatomaceous earth, fullers earth, activated carbon and activated clay; about 1.4% of a corrosion inhibitor selected from the group consisting of a soluble alkali metal chromate and dichromate and about 28.6% of water to dissolve the inhibitor and impregnate the particulate material therewith, and applying a coating of the resulting composition to the surfaces to be protected from corrosion so that the absorptive material retains the inhibitor in proximity to the surfaces to be protected and slowly releases the inhibitor to such surfaces in the presence of moisture and insures prolonged protection against corrosion of such surfaces.

References Cited in the file of this patent UNITED STATES PATENTS 2,568,424 Watson Sept. 18, 1951 2,838,419 Francis June 10, 1958 2,852,396 Kinneman Sept. 16, 1958 

1. A COMPOSITION FOR THE COATING OF METAL ARTICLES TO INHIBIT CORROSION THEREOF IN THE PRESENCE OF MOISTURE, SAID COMPOSITION CONSISTING ESSENTIALLY OF 35 TO 85% BY WEIGHT OF OLEAGINOUS MATERIAL SELECTED FROM THE GROUP CONSISTING OF SULPHONATED OIL, PETROLATUM, LARD OIL, LINSEED OIL, TUNG OIL, SOYA BEAN OIL AND MIXTURES THEREOF, 5% TO 40% OF A SOLID ABSORPTIVE PARTICULATE MATERIAL SELECTED FROM THE GROUP CONSISTING OF DIATOMACEOUS EARTH, FULLER''S EARTH, ACTIVATED CARBON AND ACTIVATED CLAY; .5% TO 2.5% OF A CORROSION INHIBITOR SELECTED FROM THE GROUP CONSISTING OF A SOLUBLE ALKALI METAL CHROMATE AND DICHROMATE AND SUFFICIENT WATER TO DISSOLVE THE INHIBITOR AND IMPREGNATE THE PARTICULATE MATERIAL THEREWITH. 